2.1 Medical Need
Neoplastic disease, such as cancer, can be caused by infectious agents, such as viruses, or so-called oncogenic viruses. Oncogenic viruses can be DNA viruses, such as Adenovirus, RNA viruses, such as Hepatitis C virus, or retroviruses, such as Human T-lymphotropic virus.
Human papillomavirus (HPV) is a DNA virus from the papillomavirus family, which has been found to be associated with several types of cancer. Although most HPV infections are subclinical and cause no physical symptoms, subclinical infections can become clinical and cause benign papillomas (such as warts or squamous cell papilloma), or cancers in certain populations. Over 170 HPV types have been identified and are referred to by number (Bzhalava et al., 2013, Virology 445 (1-2): 224-31). There is currently no cure for HPV infections.
About a dozen HPV types (including types 16, 18, 31, and 45) are called “high-risk” types because they can lead to cervical cancer, anal cancer, vulvar cancer, vaginal cancer, and penile cancer (Parkin et al., 2002, CA Cancer J Clin 2005; 55:74-108). It is estimated that 99.7% of all cervical cancers are caused by high-risk oncogenic HPV types (Ault, 2006, Infectious Diseases in Obstetrics and Gynecology 2006: 1-5), including HPV type 16 and HPV type 18, which together account for about 70% of cervical cancers (See World Health Organization's website on HPV and cervical cancer, and the Center for Disease Control's “Pink Book” on HPV). Several types of HPV, in particular type 16, have also been found to be associated with HPV-positive oropharyngeal cancer (OSCC), a form of head and neck cancer (D'Souza et al., 2007, N. Engl. J. Med. 356 (19): 1944-56). Overall, HPV type 16 is the most problematic genotype associated with at least half of all cervical cancers and the great majority (approximately 90%) of the HPV-associated cancers at other anogenital sites and the oral cavity (Peng et al., 2014, Cell Biosci., 4(1):11).
It is estimated that in 2002 about 5.2% of all new cancers worldwide (561,200 new cancer cases) were attributable to HPV, making HPV one of the most important infectious causes of cancer (Parkin, 2006, Int. J. Cancer 118 (12): 3030-44). Cervical cancer is the second most lethal form of cancer in women worldwide, with nearly half a million women diagnosed each year (Parkin et al., 2005, CA Cancer J Clin; 55:74-108).
In developed countries, effective national programs for cytologic (Pap) screening for the precursor lesion, high-grade cervical intraepithelial neoplasia (CIN), have been established. Such cytologic screening is usually followed by ablation of preinvasive lesions by conization or loop electrosurgical excision procedure (LEEP), which has reduced the incidence of cervical cancer by approximately 70-80% in the US, such that there are now approximately 5000 cervical cancer deaths each year (Roden et al., 2006, Nat Rev Cancer; 6:753-763). In cases where cervical cancer has already established, the primary treatment is radical hysterectomy and surgical debulking, followed by chemoradiation therapy. Even after undergoing this conventional therapy, which has significant unwanted side effects, patients with advanced cervical carcinoma still have a poor prognosis. Therefore, novel therapeutics specifically targeting cancerous cells while leaving normal cells unaffected, are still urgently needed for the treatment of established cervical cancer.
In addition, therapeutic vaccines would also be valuable to ensure viral clearance in patients with persistent HPV infection, which presents a necessary, though not sufficient cause of uterine cervical carcinoma, both squamous cell carcinoma and adenocarcinoma (zur Hausen et al., 2002, Nature Rev Cancer 2002; 2:342-350; Schiffman et al., 1993, J Natl Cancer Inst, 85:958-964; Walboomers et al., 1999, J Pathol, 189:12-19). Molecular testing for oncogenic HPV infection has recently been licensed as an adjunct to cytologic screening (Schiffman et al., 2007, Lancet, 370:890-907), and patients tested positive for HPV infection could significantly benefit from therapeutic vaccination.
2.2 HPV Vaccines
Two prophylactic multivalent HPV L1 virus-like particle (VLP) vaccines, i.e., Gardasil® and Cervarix®, preventing oncogenic HPV infection (Roden et al., 2006, Nat Rev Cancer, 6:753-763), HPV related cervical neoplasia, and genital warts, have been approved by the Food and Drug Administration (FDA) and the European Medicines Agency (EMA). These vaccines are believed to prevent HPV related disease by induction of neutralizing antibody responses, but they do not, however, alter the course of pre-existing HPV infections (Hung et al., 2008, Expert Opin Biol Ther., 8(4): 421-439). Thus, there is still a compelling medical need for the development of effective immunotherapeutics that could be used for therapeutic elimination of chronic HPV infection as well as for treatment of established HPV-related cancers.
The HPV early proteins (E1-E7) are expressed throughout the viral life cycle, are only present in infected cells, and are involved in regulation of disease progression. Proteins E6 and E7 are known to act as oncogenes that promote tumor growth and malignant transformation. The expression of these viral oncoproteins has been reported to be necessary to maintain the transformed phenotype of cervical cancer cells (Goodwin et al., 2000, Proc Natl Acad Sci USA 97:12513-12518; Goodwin et al., 2001, Cell Growth Differ., 12:525-534).
2.3 Recombinant LCMV Expressing Genes of Interest
The generation of recombinant negative-stranded RNA viruses expressing foreign genes of interest has been pursued for a long time. Different strategies have been published for other viruses (Garcia-Sastre et al., 1994, J Virol 68(10): 6254-6261; Percy et al., 1994, J Virol 68(7): 4486-4492; Flick and Hobom, 1999, Virology 262(1): 93-103; Machado et al., 2003, Virology 313(1): 235-249). In the past it has been shown that it is possible to introduce additional foreign genes into the genome of bi-segmented LCMV particles (Emonet et al., 2009, PNAS, 106(9):3473-3478). Two foreign genes of interest were inserted into the bi-segmented genome of LCMV, resulting in tri-segmented LCMV particles (r3LCMV) with two S segments and one L segment. In the tri-segmented virus, published by Emonet et al., (2009), both NP and GP were kept in their respective natural position in the S segment and thus were expressed under their natural promoters in the flanking UTR.
2.4 Replication-Deficient Arenavirus Vectors
The use of infectious, replication-deficient arenaviruses as vectors for the expression of antigens has been reported (see Flatz et. al., 2010, Nat. Med., 16(3):339-345; Flatz et al., 2012, J. Virol., 86(15), 7760-7770). These infectious, replication-deficient arenaviruses can infect a host cell, i.e., attach to a host cell and release their genetic material into the host cell. However, they are replication-deficient, i.e., the arenavirus is unable to produce further infectious progeny particles in a non-complementing cell, due to a deletion or functional inactivation of an open reading frame (ORF) encoding a viral protein, such as the GP protein. Instead, the ORF is substituted with a nucleotide sequence of an antigen of interest. In Flatz 2010, the authors used infectious, replication-deficient arenaviruses as vectors to express OVA (SIINFEKL epitope). In Flatz 2012, the authors used replication deficient arenaviruses as vectors to express HIV/SIV Env.
Provided herein are infectious arenavirus vectors, including an infectious, replication-deficient arenavirus viral vector, a replication-competent tri-segmented arenavirus viral vector, and a replication-deficient tri-segmented arenavirus viral vector, or an arenavirus genomic segment to treat or prevent a neoplastic disease, such as a neoplastic disease caused by infection with oncogenic viruses.